1. Field
One or more embodiments of the present invention relate to an anode active material, a method of preparing the anode active material, and a lithium secondary battery including the anode active material.
2. Description of the Related Art
Lithium secondary batteries are used in portable electronic devices for mobile communication, such as mobile phones, notebook computers, electric bicycles, or electric vehicles, and may have a relatively higher energy density than conventional batteries.
Lithium secondary batteries produce electrical energy by oxidation and reduction reactions that occur when lithium ions are intercalated to or deintercalated from a cathode and an anode, said cathode and anode each including an active material that enables the intercalation and deintercalation of lithium ions, and having an organic electrolyte or a polymer electrolyte filled therebetween.
An anode active material, for example, an oxide that includes lithium and a transition metal and has a structure enabling intercalation of lithium ions may be used in a lithium secondary battery. Examples of an oxide that may be used as a positive active material include, but are not limited to, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and lithium nickel cobalt manganese oxide (Li[NiCoMn]O2, Li[Ni1-x-yCoxMy]O2).
A typical anode active material that is used (utilized) in a lithium secondary battery may be selected from carbonaceous materials, such as artificial graphite, natural graphite or hard carbon, and non-carbonaceous material, such as Si.
Thus, non-carbonaceous materials have been recently investigated as a negative active material for lithium secondary batteries. However, their volumetric swelling or shrinkage during charging and discharging of a lithium battery may lead to a decrease in capacity retention ratios, charging/discharging efficiency, and lifespan characteristics. Accordingly, there are limitations to using (utilizing) known carbonaceous and non-carbonaceous materials as high-performance negative active materials for lithium batteries.
As demand for lithium secondary batteries with a high capacity has increased, developments have been made to increase a capacity of an anode active material. In this regard, there is a need to develop high capacity metal materials, such as silicon and tin, and alloy materials thereof.